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Contract#IRL2019-18 Encumbrance#GL01-1736/GL01-1895 ATTACHMENT A-STATEMENT OF WORK PROJECT TITLE: Lost Tree Islands Conservation Area Ecological Enhancement Plan Design and Engineering II. INTRODUCTION/BACKGROUND: Serious threats to the health of the Indian River Lagoon(IRL)include reduced water quality due to manmade hydrologic changes, projected impacts due to extreme weather events and climate change, non-point source pollution, loss and fragmentation of habitats, overuse/overharvest of resources, and the continued invasion by invasive exotic species. Less apparent forms of direct habitat loss also impact the IRL. For example, more than 40,000 acres of highly productive salt marsh and mangrove marsh have been converted into mosquito impoundments. Both the productivity and the nursery habitat value of impounded marshes are lost to the rest of the IRL. Recent storms such as Hurricane Matthew (2016) and Irma (2017) have resulted in significant damage to developed and undeveloped lands within,and abutting,the Lagoon.Most recent studies and models indicate that there will continue to be an increase in the frequency of hurricane landfalls in the southeastern US.Anticipated impacts from hurricanes to Lagoon habitats include excessive pollutant loading from large volumes of stormwater runoff, algal blooms, fish and invertebrate mortality,aquatic animal displacements,large scale releases of chemical pollutants and debris,and exacerbated spread of exotic species by colonization of scoured areas. It is fortunate that many ecological components of estuaries and coastal systems, although initially severely altered by hurricane damage, appear to be resilient to the acute effects of periodic hurricanes. The concern, however, is how to take actions that bolster resiliency and sustainability of these systems as the frequency of these storms increases and there is reduced time for recovery. This issue is further complicated by anticipated sea level rise and other climate change related effects such as increases in ambient water temperatures. Impacts from sea level rise will directly affect the ecology, hydrodynamics, circulation patterns, depth and salinity of the IRL. Fringing mangrove communities serve to stabilize sediments and provide habitat and nursery area for numerous fish and invertebrates.These mangrove communities have adapted to maintain their location along the interface between the Lagoon and upland areas by accreting sediment at a rate in tune with sea level rise (as it occurs at a relatively slow pace). Accelerated sea level rise could result in significant loss of buffering mangroves by outpacing their ability to accumulate sediments at appropriate rates. Similar to mangrove wetlands, seagrass beds are critical to the overall health and water quality of the Lagoon. They provide sediment stabilization and habitat for a variety of marine species. Seagrass beds oxygenate the water column,provide substratum for epiphytes and are a food source utilized by manatees, urchins, conchs, some fish and sea turtles. Increased water depths in the Lagoon may reduce light penetration and adversely impact the photosynthetic capacities of seagrasses leading to substantial decreases in seagrass coverage. Further complicating the loss of seagrass habitat,increases in salinity levels are known to adversely affect the larval stages of some estuarine invertebrate organisms thereby reducing their abundance and diversity. Loss of these invertebrates will dramatically impact the food web in the Lagoon.Biodiversity as a whole will be reduced as sea levels rise and warmer water temperatures and native species are displaced by invasive and other opportunistic organisms. Municipalities along the east coast of Florida Indian River County have witnessed the ecological changes in the Lagoon that are attributable to coastal development. It is becoming apparent that these changes are exacerbated by the frequency of extreme storms. For example, Indian River Page 13